Unit B

Module 3 ~ Lesson 1

Ecosystems

All of the biotic and abiotic components in the environment make up an ecosystem, and all the ecosystems in the world and their interactions make up the biosphere. Living organisms are found high in the atmosphere, deep in the ocean, and below the soil layer. This area on Earth where living organisms are found is called the biosphere. The term biodiversity refers to the variety of different species of organisms and ecosystems that exist in an area.

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Watch

Watch this video for an introduction to ecology.

Change

Habitats can change over time due to changing abiotic conditions, the effect of organisms, or natural disasters.

An area that was once suitable for trees can be made unsuitable by fire, rockslides, or a variety of other disturbances. The new habitat created by these disturbances may be less suitable for trees but will be more suitable to other species, such as moss and lichens. Over time, the moss and lichens can change the habitat so that it once again becomes suitable for shrubs and grasses to grow.

The graph to the right shows how the types of species change as time passes. The graph describes a habitat recently exposed by a melting glacier.

The abundance and distribution of organisms are also dynamic. Population size may fluctuate due to changing abiotic conditions, natural disasters, predation, seasonal changes, availability of food, or a variety of many other factors.

Self-Check

Why does it take over 100 years for trees to appear in the habitat in the above graph?

It takes a long time for the nutrients in the soil to build up so that they could supply enough nutrients to support the extensive root system of a tree.

What are some abiotic conditions that could influence the size of the leaves on a plant?

Amount of moisture, amount of nutrients in the soil, available sunlight, temperature

Read

Read "Environments Change Over Time", "Ecosystems" and "The Bigger Picture: Earth's Biosphere" on pages 81 to 83 of your textbook.

Case Study

Read "The Mountain Pine Beetle vs an Ecosystem" on page 77 of your textbook. At the end of this module, you will be asked to design a field study comparing the biotic and abiotic components of two ecosystems. As you read the case study on pine beetles, make sure that you can identify the biotic and abiotic components of the mountain ecosystem.
For more information on pine beetle infestation in Alberta, read this article from the Government of Alberta and watch the video below.